A cast steel three-piece bogie is the most common bogie type in a rail wagon.
As shown in FIG. 1, a bogie in prior art comprises a body 10′ of a swing bolster, friction blocks 20′, vertical elastic elements 40′, upright post wearing plates 70′, slope wearing plates 90′ and a side frame 80′, wherein there are two friction blocks 20, the body 10′ of the swing bolster is matched with the two friction blocks 20′ through sloped portions, and the body 10′ of the swing bolster is positioned between the two friction blocks 20′, the slope wearing plates 90′ are arranged on the body 10′ of the swing bolster, and each of the slope wearing plates 90′ is positioned between the body 10′ of the swing bolster and each of the friction blocks 20′; the upright post wearing plates 70′ are in friction fit with the friction blocks 20′; the vertical elastic elements 40′ are arranged below the body 10′ of the swing bolster and the friction blocks 20′, and the body 10′ of the swing bolster, the friction blocks 20′, the vertical elastic elements 40′, the upright post wearing plates 70′ and the slope wearing plates 90′ are all arranged on the side frame 80′.
The weight of a wagon body acts on the vertical elastic elements 40′ through the body 10′ of the swing bolster, the vertical elastic elements 40′ are used for alleviating impact force from a rail and disturbing force of vibration, and a function of preventing system vibration is realized because the direction of acting force of the vertical elastic elements 40′ is opposite to its movement direction. Meanwhile, under the action of acting force of the wagon body and counterforce of springs, certain pressure may be generated between the upright post wearing plates 70′ and the friction blocks 20′ and between the slope wearing plates 90′ and the friction blocks 20′. In a vibration process of the wagon body, relative movement and friction may be produced between the upright post wearing plates 70′ and the friction blocks 20′ and between the slope wearing plates 90′ and the friction blocks 20′, so that vibration kinetic energy is converted into friction heat energy to fulfil the aim of reducing the vibration and impact of a wagon.
The slope wearing plates 90′ may be thinned after long-term friction between the body 10′ of the swing bolster and the friction blocks 20′, which causes the upward movement of the friction blocks 20′ to further reduce compression amounts of the vertical elastic elements 40′ and namely reduce vibration reduction capabilities of the vertical elastic elements 40′. Particularly during unloaded running of the bogie, the compression amounts of the vertical elastic elements 40′ are small, so that a poor vibration reduction effect and a potential running safety hazard during the unloaded running of the bogie are caused.